In order to perpendicularly cut a web of material, the most common solution is to have a carbide blade that is fixed on a steel cylinder. There are different kinds of shapes for the blades: for example, a carbide tip brazed on a steel support; a square piece of carbide with sharpened angles; and a carbide blade with two or more useful cutting edges.
These solutions have some drawbacks. The lifetime of the blades is quite short, i.e., from one week to one month. Moreover, since the entire edge length of the blade needs to touch the counter-knife at the same time, high forces are needed to get the cut. This creates shocks and vibrations and damages the counter-knife. The blade(s) also need to be adjusted in height and to be aligned prior to cutting in order to get a good cut. However, the price of such an arrangement is a main advantage.
It is known to angle the knife edge on the rotary cutter, see U.S. Pat. No. 3,380,328, EP288182A1 and U.S. Patent Application Publication No. 2007/0044613. However, because the knife or cutting edge is fixed to the rotary cutter, the angle of the cut on the web is not adjustable, i.e., a plurality of interchangeable, different angled knife edge/rotary cutters are needed to achieve different angles of cuts. Moreover, such devices merely orient the cut via the angled cutting edge, but not the cutting unit itself. Also, the rotation axis of the cutter is limited to being positioned in a predetermined orientation to the feed direction of the web.
The foregoing, as well as the following detailed description of the embodiments, will be better understood when read in conjunction with the appended drawings. It should be understood that the embodiments depicted are not limited to the precise arrangements and instrumentalities shown.